Research

PI - Hazel Barton

Dr. Barton is an Associate Professor of Biology and Geosciences at the
University of Akron. Her current research is geared toward understanding
microbially driven geochemistry in cave environments, with funding from the US
National Science Foundation (NSF) toward understanding how bacterial adapt to
the extreme isolation and nutrient limitation of caves. Other funding
from the US Fish and Wildlife Service is to study the natural history and
ecology of Pseudogymnoascus destructans, the causative agent of
White-nose Syndrome, a devastating mycosis of bats within the northeastern US,
while the National Park Service provides funding to understand microbial
adaptations in subterranean lakes deep within Wind Cave, South Dakota. Through
this work and her interest in undergraduate research, Dr. Barton’s lab has been
awarded a ‘top ten research labs for undergraduates’ designation by Popular
Science magazine in 2010, 2011 and 2013.
Dr. Barton is also an avid caver, having explored caves on five
continents, is a past director of the National Speleological Society (NSS), the
Quintana Roo Speleological Survey, and an award winning cave cartographer. Her
cave research has been featured in Sports Illustrated, Forbes, National
Geographic Explorer, Outside, Science News,The Scientist, Popular
Mechanics, Wired, Geo and The Smithsonian magazines, in
the book Extreme Scientists: Exploring Natures Mysteries from Perilous
Places, on NPR and BBC Radio, on Animal Planet, the History Channel,
the CBS Early Show, BBC TV and in the IMAX movie Journey into Amazing Caves.
She is currently a Fellow of the NSS, a Kavli Fellow of the American Academy
for the Advancement of Science, and the recipient of an NSF CAREER Award.

Dr. Hannah Reynolds

Jessica Lee, Chef

My research goals are to understand the physiological response to starvation of microorganisms, both at the community level (between physiologies, with the environment and the role of community evolution and adaption) and individual level (metabolic and genomic adaptation).

— Dr. Hazel Barton

Applied Research: White-Nose Syndrome

Since 2006 an emerging infectious disease, caused by the fungus Geomyces destructans, has decimated cave hibernating bat populations of the Eastern US. The conidia of G. destructans create a powdery, white appearance on the muzzles of infected bats, which has led to the disease being named White-Nose Syndrome (WNS). This fungus appears to disturb bats during the hibernation period, leading to a loss of critical fat reserves and death from starvation and/or dehydration. At the present time, it has been estimated that with the continued spread of this pathogen, the once common Little Brown Bat (Myotis lucifugus) may go extinct within the next 20 years; eight other bat species are also threatened. As cave microbiologists, we are helping Federal wildlife managers understand the microbiological and logistical issues of this disease, including the development of decontamination protocols and techniques geared toward saving hibernating bats in impacted caves. Our work also includes studying the role that fungi, and in particular Geomyces spp., play in cave environments. For more information on WNS follow this LINK.

Physiological Adaptation to Starvation: The Role of the Community

Despite the rapid expansion in microbial ecology within the last twenty years, there has been little trying to tie current ecological paradigms to the microbial world. Rather, microbial ecology has continued to expand the size, rather than type, of analyses. In starved microbial ecosystems, there is often a disparity between nutrient availability and diversity, which was first described by Hutchinson in 1961 as the “paradox of the plankton." Microbial ecologists have attempted to explain this phenomenon by arguing that local dispersion, competition or nutrient flux account for this high species richness. Similar diversity is also observed in cave environments, yet the stability of caves over geologic time scales argues against dynamic niche states as an explanation for such diversity. We are therefore examining the role that diversity may play in the efficiency of nutrient acquisition and metabolic activity. While metagenomic approaches would ideally be suited to understanding the integration of physiologies within these environments, the low biomass of the samples (<105 data-preserve-html-node="true" cells/g) and the difficulty in DNA extraction currently preclude this approach. We have therefore been looking at how geochemistry (nutrient and potential sources of energy) affect microbial community structure, and how the complexity of a microbial community effects substrate utilization under different nutrient levels. To examine such systems, my lab uses a combination of traditional molecular phylogenetic approaches (using the full-length 16S ribosomal RNA gene sequence) and high-throughput 16S V6 tag sequencing (using a 454-pyrosequencing). Future studies will include specific manipulation of microorganisms, both in microcosms and in the environment, to examine the effect of diversity on metabolic efficiency and rates of species recruitment and retention.

Physiological Adaptation to Starvation: The Role of the Individual

My research lab has generated a bacterial cultivar library containing in excess of 4,000 cave isolates from a number of different caves. These isolates have also allowed us to ask questions regarding the physiology of starvation and evolutionary adaption. Given the predominance of calcium ions in caves (caves are comprised of calcium carbonate rock), we are currently examining the effect that calcium has on microbial physiology. By using a combination of environmental isolates, functional gene analysis, stable-isotope probing and gene knock-outs, our work suggested that species isolated from cave environments have adapted to potentially toxic levels of calcium by precipitating calcium carbonate crystal polymorphs. This adaptation appears to be genetic in origin and distinct from the proposed role of lcfA (first described in Bacillus subtilis) in fatty acid oxidation. Subsequent work suggests that by altering the chemical conditions in which these minerals precipitate, microbial physiology can actually influence the type of mineral deposit that is made, dramatically affecting the structure of secondary deposits (speleothems) within the system. This cultivar library has also proved to be remarkably fruitful in a number of collaborations, including: 1) a culture and genomic screening library for antibiotic production; 2) a culture library to determine the extent of the antibiotic resistome in closed, natural systems; 3) a screening library to examine novel polymer production; and 4) examination of denitrification under geochemical conditions.

Comparative Genomics

In order to understand physiological adaptations at the individual level, we are also carrying out comparative genomics to determine whether starvation and local geochemistry leave a genomic imprint on cave microorganisms. To date, we have fully sequenced (using 454-pyrosequencing) and partially assembled the genome of the cave isolate Pseudomonas fluorescens R124 and we have sufficient structural data to demonstrate that the genome has undergone significant rearrangements, including the acquisition of two major genomic regions. We are in the process of comparing three other cave P. fluorescens from different geochemical conditions through a combination of Illumina and 454-sequencing. To assist with sequence assembly, we have developed Scaffolder, a sequence assembly program LINK.